Electrical gremlins on new to me '98 Laramie

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yer_muther

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Background: I bought the truck super cheap because it had sat a few years and wasn't running. I put an alternator on it (wrong one 90A) and it wouldn't run. A new ground to the fuel pump fixed that up.

I took it for a spin today and when I was checking out systems I tried to turn the wipers on and the truck stopped charging. The wipers didn't work either.

I'm at a loss as to what to look at. I threw the charger on the battery and it showed only 8 volts after I messed around a bit. I imagine the battery which was from my old jeep has died but why would trying the wipers make it stop charging?

Since I had one bad ground what others can I check? I already cleaned up the one on the motor and the end at the fuse panel under the hood.

I love this rust bucket already but I hate chasing electrical gremlins. Any help would be fantastic!
 

Spike95

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Do you have a voltmeter or amp clamp to test if the alternator is actually charging?

Also, there will usually be ground connections on the firewall in the engine bay. Not sure on your truck, but that is pretty universal.

if things literally quit working the moment you turned wipers on, then you likely have a short in the wiper circuit. First sign there would be a blown fuse. That affecting the charging circuit is weird though. I would look for two wires chaffed and rubbing together between the charging and wiper circuits.
 
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yer_muther

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Thanks for moving me to the right place. :) I do have a voltmeter and I checked it just now and it is charging but the battery is so sketchy it's not working well I guess. Time for a new battery.

I searched everywhere for a body ground and be darned if I see one but I guess I'll have to look harder. I'm hoping someone can just say "look right here".

If I'm guessing I'd say the little extra draw was enough to cause the battery to flake out and everything else. The wipers aren't working at all and I'll have a look for shorts.

As an aside , can you think of any problem having the 90A versus the 123A might cause.
 

Spike95

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That depends on how much power you’re using. It might be okay, but wouldn’t recommend ever hooking up any extra lighting or other electrical accessories... especially no electric fan conversions.
 
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yer_muther

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Thanks for the info. I wanted to make sure I wasn't doing anything horrible with the smaller alternator. I can handle swapping it out later. Looks like I've got my work cut out for me. :)
 

multimopes

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Have you found anything? I hope you have fixed the problem and just forgot about your post here.
 

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